Spring motor operated tilting toy dump truck



Aug. 18, 1964 D. J. BLAHNIK 3,145,056

SPRING MOTOR OPERATED TILTING Toy DUMP TRUCK Filed March 2, 1959 lil-w. O

United States Patent C) 3,145,056 SPRHNG MTR @PERATED TILTING TY DUMP TRUQK David .1. Blahnik, @Crystal Lake, Eli., assigner, by mesne assignments, to .loseph H. Carter, Rockford, Ill. Filed Mar. 2, 1959, Ser. No. 796,666 Claims. (Cl. 293-22) This invention relates to a hydraulic piston and cylinder mechanism especially designed and adapted as a spring motor for operating the dump body of a toy dumptruck but also suitable for use in door-checks and closers, and the like.

Toy dump-trucks with hydraulically operated pistons for operating the dump body, as heretofore designed, had the piston operable directly by spring pressure in the event the oil or other fluid used for checking the piston movement happened to leak out, and a child could easily sustain a serious injury by coming into contact with the dump body when it was volently thrown upwardly upon release of the catch under those conditions. As a matter of fact, injuries traceable to this cause became so common that many retailers refused to deal any longer in hydraulic toys. It is, therefore, the principal object of my invention to provide an improved construction in which the working piston is always operable at slow speed and solely by the oil or other fluid, and in the event any of the oil is lost by leakage the only effect noticeable `is a reduction in the length of the stroke of the piston; there is no longer any possibility of injury to the operator in the manner described.

A single elongated two-compartment cylinder is provided in accordance with my invention, having the work-v" ing piston operable in one compartment, and a springpressed piston operable in the other compartment, while a check-valve is disposed in a partition provided between the two compartments, which unseats in the return stroke of the working piston to allow the oil or other fluid employed to escape quickly from in front of this piston and enter the other compartment, where it forces the piston therein to the rear, compressing the power spring. Upon release of lthe catch holding the dump body down, the working piston is moved by the incoming oil delivered under pressure of the power spring through a bleeder hole as the check-valve seats, closing the main larger port. Consequently, the working piston is operated slowly on the working stroke and can never be operated otherwise, and the length of its stroke is determined entirely by the amount of` oil or other fluid available.

The invention is illustrated in the accompanying drawing, in which- FlG. l is a perspective view of a toy dump-truck equipped with a hydraulic piston and cylinder mechanism made in accordance with my invention for operating the dump body;

FIGS. 2 and 3 are longitudinal sections through the piston and cylinder mechanism, FIG. 2 showing the parts at the end of a dumping operation, and FIG. 3 showing the parts before a dumping operation;

FiG. 3a is an enlargement of the middle portion of FiG. 2 to better illustrate the construction, and

FlG. 3b is a cross-section onV the line b-b of FIG. 3a.

The same reference numerals are applied to corresponding parts throughout these views.

Referring to the drawing, the toy dump-truck indicated generally by the reference numeral 4 is of fairly conventional design and construction, and is shown equipped with a hydraulic piston and cylinder mechanism or spring motor made in accordance with my invention and indicated generally by the reference numeral 5, there being a horizontal cross-pin (not shown) suitably supported on the frame 6 extending through diametrically opposed holes 7 provided in one end of the elongated two-compartment cylinder 8 for pivotal connection of the mechanisrn with the frame 6, while the Working piston 9 has a hole 16 provided in the outer end of its rod 11 for pivotal connection with another horizontal pin on the bottom of the dump body 12 intermediate the ends thereof, whereby to tilt the body rearwardly at 13 on its pivoted rear end for dumping, as seen in FIG. 1. The frame 6 is referred to elsewhere herein as one of two relatively movable parts and the dump body 12 as the other of said two relatively movable parts. A catch A, pivotally mounted on `the frame 6, is engageable with a lug B provided on the front end of the dump body to lock the latter in its normal loading position until the release lever C is swung forwardly by the operator to release the catch and allow the dump body to be tilted by means of the working piston 9 under hydraulic pressure.

Absolute safety of operation is assured with the mechanism 5 of my invention, because the piston 9 is not operated directly by a spring, as in the prior constructions referred to above, but depends` for its operation solely upon the delivery of oil or other working fluid under pressure but at a controlled rate to compartment 14 from compartment 15 by means of a piston 16, under pressure of the power spring 17, the piston and springbeing both contained in the second compartment 15. A check-valve 1d engages a conical seat 19 to close a large main central port 2i) provided in the partition 21 between the two compartments, whereby to prevent too fast movement `of the working piston 9 on its working stroke, the oil or other fluid in this operation bleeding fairly slowly-through the relatively restricted bleeder hole or port 22, so that there is no danger whatever of injury to the operator. If any oil is lost by leakage past either of the pistons 9 and le the only effect noticeable is a shorter travel of the working piston 9 on the working stroke, and, in order to reduce leakage of oil to a minimum, O-rings 23 are provided in annular grooves in the periphery of the piston 16, and another O-ring is provided, as at 2li, in an annular groove in the periphery of the working piston .9.

A cylindrical plug 25 having a press lit in the tubing forming the cylinder 8 closes one end of the cylinder and has a center hole 26 therein through which the piston rod 1li extends with a free fit, so that there is no air-cushion action as the working piston` 9 operates on its working stroke. A washer 27, `held in place by diametrically opposed struck-in lugs 28 cut from the `wall of the tubing forming the cylinder 3, serves as an abutment for the outerend of the power spring 17 behind piston 16; The center hole 29 in the washer 27 allows free inflow and outflow `0f air as the piston 16 moves back and forth, thus eliminating any air-cushioning action there.

The cylindrical plug 21 forming the partition between compartments 1li and 15 may be retained in place in any suitable mannerbut is shown as having a close, tinthe bore of the tubing forming the cylinder 8 and having an annular V-groove 3i) into which an annular portion V31 of the wall of the tubing is swedged to prevent endwise displacement of the plug and also seal the joint annularly between the plug and the Wall of the tubing. A small fill pin 32 entered with a drive fit in registering holes provided by drilling `through the wall of the tube and into the plug 21 into register with an .annular groove 33 provided in one side of the plug serves to seal the compartment 14 after two compartments 14 and 15 have been supplied with the requisite amount of oil or other fluid needed for the hydraulic operation of the mechanism. The pin 32 also serves as a key to prevent turning of the plug 21 relative to the cylinder. A disk 34 having a plurality of holes 35 provided therethrough is entered with a press fit llatented Aug. 18, 1964` in the center hole 36 provided in the plug 21, whereby to retain the ball 18, serving as the check-valve, and yet allow fairly unrestricted flow of oil from compartment `14 into compartment 15 in the return stroke of the working piston 9. r

In operation, assuming the dump body 12 is in its normal loading position, the parts of the piston and cylinder mechanism are disposed as seen in FIG. 3, with the power spring 17 loaded as a result of the previous return movement of the dump body 12 by hand. When the catch A is released, oil under pressure of the spring 17 is delivered at a predetermined rate through the bleeder hole 22, the check-valve 18 being, of course, seated by .the oil pressure thereon and closing the large central port 20. The working piston 9 is accordingly moved outwardly at a reasonably slow speed, swinging the dump body 12 upwardly, simulating the operation of a large dump-truck. There is no danger whatever of the piston 9 moving too fast and causing a child to be injured by reason of violent upward movement of the dump body 12, as described above. If any of the oil leaks out, the dump body 12 will be tilted as before but not quite as far. In the reseating of the dump body the piston 9 moving inwardly fairly fast expels the oil from compartment 14 past the open check-Valve 8 into compartment 15, forcing the piston 16 outwardly and loading the power spring 17.

In closing, it should be obvious tha-t the hydraulic piston and cylinder mechanism 5 could be used also in a door check or door closer, and wherever a piston operable in the manner herein described is required or would be of advantage.

It is believed the foregoing description conveys a good understanding of the objects and advantages of my invention. The appended claims have been drawn to cover all legitimate modifications and adaptations.

I claim:

1. A dual piston and cylinder structure comprising two cylinders in rigid coaxial and coextensive relationship, a partition Wall separating adjoining inner ends of said cylinders, end walls closing the outer ends of said cylinders, one of said end walls having an opening provided therein, a piston rod extending through and reciprocable in said opening and connected with a piston reciprocable in one of said cylinders, a piston reciprocable in the other of said cylinders, a coiled compression spring in the latter cylinder compressible between said piston and the outer end wall of said cylinder, the inner ends of said cylinders being in communication through openings provided in said partition wall, and check valve means cooperating with said openings and housed in said partition wall to control fluid iiow between said cylinders to provide a certain llow rate in one direction between said cylinders with said check valve means seated and a different flow rate in the opposite direction with said check valve means unseated.

2. A structure as set forth in claim l, including hydraulic fluid in said cylinders between said pistons, whereby movement of one piston is transmitted through the intervening lluid to or from the other piston.

3. A structure as set forth in claim 1, including a ll opening for hydraulic fluid provided in said partition wall communicating with one of said cylinders from the outside of said cylinders, and a closure for said opening.

4. A hydraulic piston and cylinder mechanism comprising a single length of tubing serving as a cylinder having means at one end for connection with one of two parts between which relative movement is to be caused, a cylindrical plug fixed in said tubing intermediate its ends 4; defining two compartments of equal diameter on opposite sides thereof in coaxial end to end coextensive relationship, a working piston reciprocable in a first compartment and having a rod guided in the other end of said cylinder for connection with the other of said parts, the plug having a port provided therein controlled by a checkvalve controlling fluid flow between the iirst and second compartments to provide a certain rate of iiow in one direction between said compartments with said check valve seated and a different rate of ow in the opposite direction between said compartments with said check valve unseated, a secondary piston reciprocable in the second compartment, a hydraulic working fluid in said compartments between the pistons, and a power spring for normally urging the second piston inwardly rtoward the iirst piston, said plug having an annular filling groove provided in one face thereof communicating with one of said compartments, there being a lill hole for injection of oil or other fluid into said last named compartment made substantially radially through the wall of the tubing into the plug intersecting said groove, and a pin'entered tightly in said hole to seal it after injection of Ithe fluid and also hold said plug against turning.

5. ln combination, a dump vehicle comprising a frame, a body pivoted with respect to said frame for tilting to dumping position, latch means releasably locking said body in lowered position relative to said frame, and a spring motor for said vehicle pivotally connected on one hand with said frame ,and on the other hand with said body, said motor comprising two cylinders in rigid coaxial and coextensive relationship, a partition wall separating adjoining inner ends of said cylinders, end walls closing the outer ends of said cylinders, one of said end walls having an opening provided therein, a piston rod extending through and reciprocable in said opening and connected with a piston reciprocable `in one of said cylinders, said rod being pivotally connected at its outer end to one of said body and frame, a piston reciprocable in the other of said cylinders, a coiled compression spring in the latter cylinder compressible between said piston and the outer wall of said cylinder, the inner ends of said cylinders being in communication through openings provided in said partition wall, and check Valve means cooperating with said openings and housed in said partition wall to control liuid flow between said cylinders to provide a certain iiow rate in one direction between said cylinders with said check valve means seated and a different ow rate in the opposite direction with said check valve means unseated, the outer end of said cylinder remote from the piston rod being pivotally connected to the other of said body and frame.

References Cited in the tile of this patent UNITED STATES PATENTS 1,144,657 Keller June 29, 1915 1,273,059 Hild July 16, 1918 1,504,505 Reed et al Aug. l2, 1924 1,602,424 Wood Oct. 12, 1926 1,723,508 Hansen Aug. 6, 1929 1,788,358 Goerg Jan. 6, 1931 1,925,461 Ridge Sept. 5, 1933 1,955,349 Stevens Apr. 17, 1934 2,471,294 Watts May 24, 1949 2,481,020 Justus Sept, 6, 1949 2,618,478 Conway Nov. 18, 1952 2,691,244 Steinke Oct. 12, 1954 2,873,994 Omps Feb. 17, 1959 2,989,299 Modrich June 20, 1961 UNITED STATES PATENT OFFICE CERTIFICATE 0F CORRECTION Patent No. 3, 145 ,056 August 18 1964 David J. Blahnik It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 3, line 6l, for the claim reference numeral "l" read Z Signed and sealed this 22nd day of June l965 (SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Altes-ting Officer Commissioner of Patents 

1. A DUAL PISTON AND CYLINDER STRUCTURE COMPRISING TWO CYLINDERS IN RIGID COAXIAL AND COEXTENSIVE RELATIONSHIP, A PARTITION WALL SEPARATING ADJOINING INNER ENDS OF SAID CYLINDERS, END WALLS CLOSING THE OUTER ENDS OF SAID CYLINDERS, ONE OF SAID END WALLS HAVING AN OPENING PROVIDED THEREIN, A PISTON ROD EXTENDING THROUGH AND RECIPROCABLE IN SAID OPENING AND CONNECTED WITH A PISTON RECIPROCABLE IN ONE OF SAID CYLINDERS, A PISTON RECIPROCABLE IN THE OTHER OF SAID CYLINDERS, A COILED COMPRESSION SPRING IN THE LATTER CYLINDER COMPRESSIBLE BETWEEN SAID PISTON AND THE OUTER END WALL OF SAID CYLINDER, THE INNER ENDS OF SAID CYLINDERS BEING IN COMMUNICATION THROUGH OPENINGS PROVIDED IN SAID PARTITION WALL, AND CHECK VALVE MEANS COOPERATING WITH SAID OPENINGS AND HOUSED IN SAID PARTITION WALL TO CONTROL FLUID FLOW BETWEEN SAID CYLINDERS TO PROVIDE A CERTAIN FLOW RATE IN ONE DIRECTION BETWEEN SAID CYLINDERS WITH SAID CHECK VALVE MEANS SEATED AND A DIFFERENT FLOW RATE IN THE OPPOSITE DIRECTION WITH SAID CHECK VALVE MEANS UNSEATED. 